Sancho I, called the Fat (d. 966), was the son of King Ramiro II of León. He succeeded his halfbrother Ordoño III in 956 and reigned until his death, except for a two year interruption from 958 to 960, when Ordoño the Wicked usurped the throne. He was a grandson of Sancho I of Pamplona and Toda Aznárez.

At first, Sancho disputed the throne with Ordoño III who had succeeded their father in 951. Upon Ordoño's death, he took the vacant throne, but only two years later he was deposed by the nobles lead by the Castilian Count Fernán González, because of his extreme obesity.

Following his exile, Sancho managed to shed at least some portion of his girth. At the same time, he began endeavoring to reclaim his throne. He first went to his grandmother Toda and asked for aid; next he concluded a treaty with the Moors and, with the help of the Leonese and Navarrese noblesse, he took Zamora in 959 and took his throne back soon afterwards.

As he did not respect his treaty with the Muslims, he experienced many punishing raids in response. The final years of his reign were characterised by the growing independence of the Castilian and Galician nobility. He was killed by poison and succeeded by his son Ramiro III.

Sancho I, called the Fat (died 966), was the son of King Ramiro II of León. He succeeded his half-brother Ordoño III in 956 and reigned until his death, except for a two year interruption from 958 to 960, when Ordoño the Wicked usurped the throne. He was a grandson of Sancho I of Pamplona and Toda Aznárez.

At first, Sancho disputed the throne with Ordoño III who had succeeded their father in 951. Upon Ordoño's death, he took the vacant throne, but only two years later he was deposed by the nobles led by the Castilian Count Fernán González, because of his extreme obesity.

During his exile in Andalus, according to Dozy, Sancho managed to shed at least some portion of his girth under the treatment of Hasdai ibn Shaprut. At the same time, he began endeavoring to reclaim his throne. He first went to his grandmother Toda and asked for aid; next he concluded a treaty with the Moors and, with the help of the Leonese and Navarrese noblesse, he took Zamora in 959 and took his throne back soon afterwards.

As he did not respect his treaty with the Muslims, he experienced many punishing raids in response. The final years of his reign were characterised by the growing independence of the Castilian and Galician nobility. He was killed by poison and succeeded by his son Ramiro III.